Qwen3.8 125B (6B active) Flash-Next

User reports Qwen3.8-Flash-Next at ~80 t/s on 3x RTX 3090 at 1M context, dropping to ~60 t/s once QSA reaches its 2048-token budget. Setup is vLLM with most of the KV cache offloaded to system RAM, no KV cache quantization. Prefill at 248k reaches 3,701 t/s, and throughput is ~150 t/s at 4 concurrent requests. Decode speed stays flat as total context grows because only 12 of 48 layers hold a KV cache and QSA bounds the per-step read to 48 MiB per token.